Field of the Invention
The present invention relates to a soot accumulation computing and displaying device that is used for regeneration processing of a filter provided in a flow path of an exhaust gas from an internal-combustion engine.
Related Art of the Invention
A DPF (Diesel Particulate Filter) is provided in a flow path of an exhaust gas from an internal-combustion engine such as a diesel engine or the like, and the exhaust gas passes through the DPF and is discharged into the atmosphere.
Herein, the DPF is a filter, which is configured with porous ceramics or the like and collects PM (Particulate Matter) that is a minute particle such as carbon or the like that is contained in the exhaust gas.
Now, since the PM collected is accumulated in the DPF, the accumulation amount of the PM increases as the driving time of the diesel engine elapses and, if the value of the accumulation amount of the PM exceeds the limiting value, a stoppage of the DPF that is called clogging is prone to be generated.
Thereupon, before the value of the accumulation amount of the PM exceeds the limiting value and an exchange of the DPF gets necessitated, regeneration processing of the DPF is conducted by burning out at high temperature the PM accumulated.
Here, more specific descriptions are given regarding the above-mentioned regeneration processing of the DPF.
In the regeneration processing of the DPF, the PM accumulated is burned out by maintaining, throughout several tens of minutes, the temperature of 600-700 degrees that is measured by a temperature sensor, which is provided on the upstream and downstream sides of the DPF.
Additionally, “600-700 degrees” means 600-700 degrees Centigrade (the same hereinafter).
This state of high temperature is realized by additionally performing post injection, using injection controlling of the injection nozzle that injects a fuel such as a light oil or the like to the cylinder of the diesel engine.
That is to say, the post injection is performed when the fuel by main injection that contributes to the engine output power is combusted inside the cylinder and the exhaust valve is opened for the purpose of discharging the exhaust gas, which has been generated by combustion, outside the cylinder.
The injection amount of the fuel in the post injection is small compared with the injection amount of the fuel in the main injection, but the fuel due to the post injection in the form of mist that is filling the exhaust gas is affected by the oxidation catalyst due to a DOC (Diesel Oxidation Catalyst) provided in the upstream side of the DPF, heat is generated, and the state of high temperature described above is realized.
Additionally, regeneration processing of the DPF is manual or automatic regeneration processing.
If the value of the accumulation amount of the PM accumulated reaches a predetermined value, primarily, automatic regeneration processing is conducted at the time of driving on the road or driving for work in the field.
However, when the load is small, since the exhaust gas temperature does not reach 600-700 degrees even if post injection is performed, regeneration processing of the DPF is not successfully conducted, and the value of the accumulation amount of the PM increases.
Then, since excess accumulation is generated, manual regeneration processing is conducted in a state where the vehicle is allowed to stop, so that the DPF will not be damaged.
The necessity of manual regeneration processing is displayed using an alert light of the instrumental panel, or a liquid crystal displaying part capable of displaying messages.
Of course, for the purpose of encouraging manual regeneration processing, the low-idling rotation number may be maintained by forcibly suppressing main injection.
Moreover, the DOC may not be provided that allows by combustion the unburned fuel to oxidize.
For example, in a case where only the DPF is provided, the exhaust gas temperature of 600-700 degrees that is measured by a temperature sensor, which is provided on the upstream and downstream sides of the DPF, is maintained using (1) controlling of the opening/closing timing of the exhaust valve and the post fuel injection timing, (2) controlling of the opening/closing timing of the exhaust valve and the post fuel injection amount, (3) controlling of the exhaust gas temperature and the post fuel injection amount, and the like.
Of course, also in a case where the DPF is provided, if the above-mentioned controlling is used, the post fuel injection is more accurately conducted, and the post fuel injection amount becomes less.
Thereupon, for the purpose of conducting regeneration processing of a DPF at an appropriate timing, known is a technology of calculating an inferred value of the accumulation amount of the PM based on the driving state of the diesel engine (for example, see Japanese Patent Application Publication No. H11-132026 and Japanese Patent Application Publication No. 2009-91915).